Metal conduits, such as gas, water and oil pipelines, can fail due to age, fatigue, corrosion, abuse, neglect and when used in the environment, natural forces that can fracture or rupture the pipe, such as seismic activity. Failure can result in uncontrolled fluid flow. A common device used to control such uncontrolled flow of fluid out of a conduit is a blow-out preventer. One or more blow-out preventers can be attached directly to the wellhead and operate to rapidly close an open well hole or the space between the casing and the drill pipe to prevent the escape of pressurized oil or gas. These devices work essentially as plugs. Ram type blow-out preventers are insertable laterally into the casing. Annular type blow-out preventers expand radially to fill the casing. Blow-out preventers are known in the art (see, e.g., U.S. Pat. Nos. 5,507,465, 5,746,249, 5,875,841 and 6,024,172). U.S. Pat. Application Pub. No. 2011/0297394 describes a magneto-rheological blow-out preventer that uses magnets and a magnetic fluid. Although blow-out preventers are effective in preventing blow-outs and any ensuing fires, if the wellhead is damaged or if conduit failure occurs before the blow-out preventers, blow-out preventers may become ineffective for stopping fluid flow.
Valves and other devices have been used in attempts to stop the flow of fluid through breached conduits. Many of the apparatus described in the art install a plug in a flowing high pressure pipeline, where the plug can, in some cases, serve as a fully operative valve. Most of these methods include a means to cut a hole through the conduit or to cut a section out of the flowing conduit, withstanding the pressure from the fluid within the conduit, and then permanently placing a plug in position. For example, U.S. Pat. No. 3,699,996 describes a device that includes a drilling and reaming tool that cuts a cylindrical hole through the flowing pipeline using a powered rotational drive and an axial hydraulic ram. A valve seat and a valve plug are positioned behind the drill and the seat automatically snaps into position upon completion of the drilling and removal of the drill bit. This apparatus requires complex sealing and locking components and requires that the drill bit be removed from the seat/plug assembly before the valve is operable. Similar devices are described in U.S. Pat. Nos. 3,532,113, 3,993,137 and 4,552,170. Some of these devices require a complex variety of seals and packings to maintain a fluid tight valve. Therefore, devices and methods that operate simply and effectively to reversibly seal a flowing high pressure conduit, such as pipeline, with a minimum of complex components, are needed.
Accordingly, a need exists for compositions, methods and devices that allow for reversibly plugging or stopping the flow of a fluid through a conduit.